Tampa, Fla. -- Crews are making progress in the hours-long fight against a massive fire at a recycling plant near Port Sutton Road at the Port of Tampa.

Hillsborough County Fire Rescue says a heap of scrap metal at OneSteel Recycling went up in flames just after 4 a.m. Monday.

The core of the fire is still burning and will be for hours, although firefighters say they do not think it will spread beyond the piles of metal that are burning right now.

Thick smoke billowed off toward the southwest all morning. People as far away as St. Petersburg could smell the smoke and see a haze in the air.

OneSteel Recycling collects scrap metal from a range of sources, then they gather the metal in a yard in the southeastern part of the Port of Tampa.

Firefighters say that metal is the only thing burning at the moment -- no equipment or buildings are involved.

About a dozen fire units from Hillsborough County responded to the scene. Hazmat and air crews backed up the more traditional firefighters, clearing a safe space around the fire to keep it from spreading.

Obviously, there are many industrial products in use at the port, so controlling the fire was critical. That done, they focused on putting it out.

Crews from OneSteel are working side-by-side with firefighters right now.

Using pieces of heavy equipment with claws on the end, workers are picking apart the burning metal so water sprayed by firefighters can get in and really hit the pieces that are still burning.

There are a pair of giant cylindrical tanks here right next to where the fire is burning. Firefighters say they're full of a fertilizer ingredient that does not burn.

On the backside of the facility, there's a diesel fuel tank. Firefighters have stationed a truck right next to it to make sure it's protected.

We just talked with the Florida Department of Health in Hillsborough County. They say there are no health concerns right now with the smoke from this fire.

The wind is moving the smoke right over Hillsborough Bay, so there's a lot of open space for it to dissipate. We don't have any word yet on what started this fire.